Targeting a bacterial mitotic spindle to combat antibiotic resistance

Bacterial multidrug resistance is a global burden on human health worldwide. Large, low copy number plasmids, implicated in antibiotic resistance, have evolved sophisticated strategies to ensure their faithful distribution at cell division. Multidrug resistance plasmids harbour their own survival system, a partition cassette, which ensures an accurate and equitable segregation of the plasmids from one generation to the next at cell division. When this system malfunctions, the plasmid is not stably inherited and is ultimately lost. The multidrug resistance plasmid TP228 replicates at low copy number in Escherichia coli. The partition cassette (~1,100 bp) of TP228 consists of the parFG genes and upstream noncoding sequence (parH) which harbours a series of related direct and invert repeat motifs. We have shown that ParF is an ATPase that assembles into extensive, multistranded filaments in vitro. The partner partition protein ParG plays at least two distinct roles in ParF polymerization dynamics: 1) it enhances ParF ATPase activity and 2) it promotes filament bundling. The recently acquired data allowed us to propose a mitotic spindle-like molecular mechanism for plasmid segregation in E. coli. This project will investigate the molecular mechanism of ParF polymerization and how ParF polymers drive DNA segregation at cell division. The study will involve molecular biology, biochemical and biophysical approaches in parallel with fluorescence microscopy to visualize DNA positioning, trafficking and segregation in the cell.